Traditionally, large storm sewers, with or without surface detention basins, have been used for handling excess storm water or runoff. However, in urban or industrial settings, the surface area on the building site is often not available or it is cost prohibitive to purchase additional surface area to accommodate systems such as open reservoirs, basins, or ponds for detaining or retaining water. Underground systems are therefore desirable because they do not utilize valuable surface areas and present fewer adverse environmental effects than other systems. In addition, underground systems are also not susceptible to the aesthetic problems, such as algae and weed growth, associated with some surface-level systems.
Many other applications exist for subsurface modular assemblies for detaining or retaining a fluid. For example, a large volume of water may be retained underground for firefighting purposes or manufacturing processing. In addition, underground storage assemblies may be used for chemical containment. Even further, these underground systems may be used as leaching chambers or for controlled release of storm water beneath the ground surface. Therefore, for ease of manufacture and installation, it is desirable to have a system that can be easily converted from a fluid retaining, to a fluid detaining, to a fluid exfiltrating system.
One problem associated with current underground systems is that, by nature, they are difficult to clean and often become clogged with debris. It is therefore desirous to provide a system that is self-cleaning and resistant to clogging and degradation caused by sand, dirt, natural materials and other debris which may be carried along with the water.
It is also desirable to have a versatile and modular assembly that may be assembled in any customized orientation to suit any plan area or footprint as desired by the particular application involved. In particular, for systems that are intended for diverting a fluid such as storm water from the ground surface to another location, the system must be able to accommodate existing or planned underground facilities such as utilities and other buried conduits.
In addition, underground systems must be adapted to resist loads imposed by other uses of the surface of the land, including the imposed by the load of the earth surrounding the system. The surface area of the land may then be used for motor vehicle parking or driving, foot traffic, an airport runway, or the like.
While other forms of underground fluid detention and/or retention structures have previously been proposed, these structures have failed to provide one or more of the above advantages.